Inasmuch as most of the patients who are candidates for the cavapulmonary artery anastomosis are children, the main objectives of this research have been to determine: (1) What will happen with growth of the individual with respect to (a) the size of the anastomosis, (b) circulation in the right (shunted) lung, (c) change in configuration of the heart with particular reference to obstruction of flow to the pulmonary artery and the left (unshunted) lung. 2) If the volume of blood passing through the shunt will change with time due to (a) a change in flow through collateral channels between the superior and inferior vena cava, or (b) a change in resistance to flow through the pulmonary circuit. Many patients with malformations of the right side of the heart with diminished pulmonary blood flow have benefitted initially from a cavapulmonary artery shunt. Long term survival of these patients may depend on the delivery of supplemental sources of venous blood to the lungs for oxygenation. The investigation of methods for the delivery of venous blood to the lungs in addition to the cava-pulmonary shunt is thus of paramount importance.